Geodynamic setting of recent volcanism in North Eurasia

Abstract

A GIS layout of the map of recent volcanism in North Eurasia is used to estimate the geodynamic setting of this volcanism. The fields of recent volcanic activity surround the Russian and Siberian platforms—the largest ancient tectonic blocks of Eurasia—from the arctic part of North Eurasia to the Russian Northeast and Far East and then via Central Asia to the Caucasus and West Europe. Asymmetry in the spatial distribution of recent volcanics of North Eurasia is emphasized by compositional variations and corresponding geodynamic settings. Recent volcanic rocks in the arctic part of North Eurasia comprise the within-plate alkaline and subalkaline basic rocks on the islands of the Arctic Ocean and tholeiitic basalts of the mid-ocean Gakkel Ridge. The southern, eastern, and western volcanic fields are characterized by a combination of within-plate alkaline and subalkaline basic rocks, including carbonatites in Afghanistan, and island-arc or collision basalt-andesite-rhyolite associations. The spatial distribution of recent volcanism is controlled by the thermal state of the mantle beneath North Eurasia. The enormous mass of the oceanic lithosphere was subducted during the formation of the Pangea supercontinent primarily beneath Eurasia (cold superplume) and cooled its mantle, having retained the North Pangea supercontinent almost unchanged for 200 Ma. Volcanic activity was related to the development of various shallow-seated geodynamic settings and deep-seated within-plate processes. Within-plate volcanism in eastern and southern North Eurasia is controlled, as a rule, by upper mantle plumes, which appeared in zones of convergence of lithospheric plates in connection with ascending hot flows compensating submergence of cold lithospheric slabs. After the breakdown of Pangea, which affected the northern hemisphere of the Earth insignificantly, marine basins with oceanic crust started to form in the Cretaceous and Cenozoic in response to the subsequent breakdown of the supercontinent in the northern hemisphere. In our opinion, the young Arctic Ocean that arose before the growth of the Gakkel Ridge and, probably, the oceanic portion of the Amerasia Basin should be regarded as a typical intracontinental basin within the supercontinent [48]. Most likely, this basin was formed under the effect of mantle plumes in the course of their propagation (expansion, after Yu.M. Pushcharovsky) to the north of the Central Atlantic, including an inferred plume of the North Pole (HALIP).